import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {
    public static int findMax(int[] arr){
        int max = Integer.MIN_VALUE;
        for(int x:arr){
            max = x>max?x:max;
        }
        return max;
    }
    public static int findMin(int[] arr){
        int min = Integer.MAX_VALUE;
        for(int x:arr){
            min = x<min?x:min;
        }
        return min;
    }
    public static boolean inrange(int x, int min, int max){
        return (x>=min && x<=max);
    }

    public static void main(String[] args) {
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
        Scanner scan =  new Scanner(System.in);
        int q = scan.nextInt();
        for(int qi = 0; qi<q;qi++){
            int n = scan.nextInt();
            int[] xarr = new int[n];
            int[] yarr = new int[n];
            for(int i = 0; i<n;i++){
                xarr[i] = scan.nextInt();
                yarr[i] = scan.nextInt();
            }
            int xmin = Integer.MAX_VALUE;
            int ymin = Integer.MAX_VALUE;
            int xmax = Integer.MIN_VALUE;
            int ymax = Integer.MIN_VALUE;
           xmin = findMin(xarr);
            ymin = findMin(yarr);
            xmax = findMax(xarr);
            ymax =findMax(yarr);
            boolean b = true;
            for(int i = 0; i<n;i++){
                if(xarr[i] == xmin){
                    if(!inrange(yarr[i],ymin,ymax)){
                        System.out.println("NO");
                        b = false;
                        break;
                    }
                }
                else if(xarr[i] == xmax){
                    if(!inrange(yarr[i],ymin,ymax)){
                        System.out.println("NO");
                         b = false;
                        break;
                    }
                }
                else if(yarr[i] == ymin){
                    if(!inrange(xarr[i],xmin,xmax)){
                        System.out.println("NO");
                         b = false;
                        break;
                    }
                }
                else if(yarr[i] == ymax){
                     if(!inrange(xarr[i],xmin,xmax)){
                        System.out.println("NO");
                          b = false;
                        break;
                    }
                }
                else{
                    System.out.println("NO");
                     b = false;
                    break;
                }
            }
            if(b)
                System.out.println("YES");
        }
    }
}